Ireland's Ryan Seaton and Matthew McGovern mastered the blustery conditions in Weymouth to move into pole position in the 49er category at the Sail for Gold Regatta.
Seaton and McGovern claimed four top-three finishes to move from sixth place to first, overtaking British duo John Pink and Simon Wheeler, to take a six-point lead with four fleet races and three double pointer medal races to go.
Seaton said: "The first race today was all about the boat handling and getting around the course nice and tidy, with the next three races all about getting the good starts and going fast which seemed to work out well for us."
McGovern, who is competing for the first time since representing Ireland at the London 2012 Olympics, added: "We were disappointed with our results yesterday as we've taken time off since the Games so were a little rusty getting back into the boat, but today our boat handling was good and were happy with our results."
Meanwhile, Charlotte Dobson and Nicola Groves took control in the 49erFX class with Kate Macgregor and Sophie Ainsworth second and France Peters and Mary Rook rounding off the British dominance in third.
Nick Dempsey, competing in the RS X windsurfing 9.5 class, added three race wins and a second place to his scorecard. The two-time world champion is second behind fellow Briton Elliot Carney overall.
In the RS:X 8.5 class, runaway leader Bryony Shaw added a further two race wins to her scorecard as did Robert York, with Izzy Hamilton remaining in third after another consistent day out on the water. Andrew Mills moved to the top of the leaderboard in the heavyweight Finn class while New Zealand's Sam Meech extended his lead in the Laser category.
Ben Saxton and Hannah Diamond continued their good form in the Nacra 17 competition to stay ahead of Lucy Macgregor and Tom Phipps, with 2008 Beijing Olympic gold medallist Pippa Wilson and her crew John Gimson in third.
Finally, Helena Lucas and Megan Pascoe are neck and neck in the 2.4mR Paralympic class at the halfway stage while John Robertson, Hannah Stodel and Stephen Thomas continued their superb run of form in the Paralympic Sonar class, with three more race wins extending their lead to five points.